Researchers to study minichromosomes in maize with $1.9 million grant

COLUMBIA, Mo. – Researchers at the University of Missouri-Columbia have been awarded $1.9 million from the National Science Foundation (NSF) to study optimal ways of creating engineered minichromosomes in maize and making additions to those minichromosomes. Their work could lead to improved development of crops that are multiply resistant to viruses, insects, fungi, bacteria and herbicides, and of proteins and metabolites used to treat human illnesses.

The five-year grant will build on previous discoveries about the creation of minichromosomes and ability to “stack” genes on them. A minichromosome is an extremely small version of a chromosome, the threadlike linear strand of DNA and associated proteins that carries genes and functions in the transmission of hereditary information. Whereas a chromosome is made of centromeres and telomeres with much intervening DNA, a minichromosome contains only centromeres and telomeres, the end section of a chromosome.

James A. Birchler, principal investigator in this study and professor, Biological Sciences, said the project’s goals are to:

Determine the optimal size of the introduced telomere for minichromosome formation,

Add visible markers to track transmission of the minichromosomes between generations,

Add a cassette to permit future modification of the minichromosomes,

Determine how many artificial minichromosomes plants will tolerate,

Add a selectable marker to ensure minichromosomes will be transferred in crosses for corn breeding.

Scientists can add numerous genes to one minichromosome and manipulate those genes easily because they are all in one place. Genetic modification with traditional methods is more complicated because scientists have little control over where the genes are located in the chromosomes and cannot stack multiple genes on a separate chromosome independent of the others.

By stacking genes on minichromosomes, scientists could create crops that have multiple beneficial traits, such as resistance to drought, certain viruses and insects, or other stresses. Minichromosomes also could be used for “biopharming,” the inexpensive production of foreign proteins and metabolites useful for medical purposes. Because of their protein-rich composition, a part of the maize kernels can be used to grow animal proteins and human antibodies that treat diseases and disease symptoms. Minichromosomes could enable new and better production of these foreign proteins and antibodies. Scientists also may be able to use them to develop plants better suited for biofuel production.

“The development and improvement of minichromosome technology will open new avenues and will enable many advances in agriculture that would not otherwise be possible, from improved crops to inexpensive pharmaceutical production to other applications in biotechnology,” Birchler said.

Birchler said this NSF-funded project will include training postgraduate, graduate and undergraduate students and hosting a conference on transgenic crops and artificial chromosome technology.